also, can i put the th350 that's in the caprice into the van? (caprice is 83 with the 305 4bbl..the van is 85 gmc vendura with 350)

thanks!

also, can i put the th350 that's in the caprice into the van? (caprice is 83 with the 305 4bbl..the van is 85 gmc vendura with 350)

thanks!

You can do either to both, but it's not plug and play. The TH350 has a vacuum modulator and a detent cable - the TH700R4/4L60 has a TV cable that's more precise (and can wreck more when improperly set) than the TH350's detent cable, which only is used for downshifting the transmission for passing (kickdown).

The transmission mounting points are not the same - the TH700R4 has its mount located an additional 3/4" rear of the TH350 point. Also, driveshaft lengths are different for the different transmissiions. The good news is that driveshafts are readily available - though you will either have to change your transmission crossmember or modify it for the new mount location point.

thanks...

I did that on a chevy c-10 truck that had 700r4, and we put in a th350..had to drill new frame holes and relocted the crossmember..i do remember having to junk yard a shaft though..

wheres a good place to get the correct driveshaft and is that something id have to take in to have r&r (i am not much of a mechanic).?

Also, the 700r4 would be more efficient? Better performance too? Any issues with the swap and do alot of people do it? the tranny is newly rebuilt with warranty and am putting a new 350 in the wagon too..

oh i did mention this was a wagon...same driveshaft as the sedan?

Wagon and sedan have the same wheelbase, and so share a driveshaft.

The TH700R4 has a lower gear, a MUCH Lower gear than the TH350 does, although the 700R4 is loosely based upon the TH350. This translates into more grunt from a stop - something that would definitely help the Caprice. There's less rotating mass in the TH700R4 than in the TH350 - this translates into less wasted power. However, there is a dark side (isn't there with everything?) - and this is the 700R4 Achilles heel - the 700R4 runs overdrive through a planetary gearset component called a Reaction Sun Shell, that indexes with the direct clutch drum - and is controlled by the 2-4 band and reverse input clutch. The hub where the shell mates with the reaction sun gear is a weak point and tends to fail, resulting in a transmission without 2nd, overdrive or reverse. The fix is a ~$50 aftermarket shell made by SPX/Filtran called a 'Beast'. If you're pulling the transmission out, you might want to consider having this replaced (as well as the rest of the transmission freshened up) so that you don't have to drop it again down the road. Having said that, the transmission in my car now (in my sig) is a 1986 model on its original factory build, with about 60,000 miles on it (10k behind my 350 lb. ft. torque engine) and so far, so good although I have a backup trans for it (that does have a Beast in it) ready to go at a moment's notice.

Don't let this scare you however; if you have a stock build 305, you're in minimal (as in infinitesimal) risk of such a failure.

thanks alot for the expertise- I am kicking around the possiblilities. I think since my 305 runs so good ill work with it and do more research on putting a 350 or big block in it. The 305 is great until it tries to kick into passing gear..hesitates, grumbles, then goes...i know it should have more torque..i feel like the carb is spittin up or something when i get on it..ive posted before without any real advice on that matter...

It's not my project, but if it were, I'd be more tempted to leave the van intact (unless it's just a dead parts vehicle) and find a core for a 700-R4 and prep it for use in the Caprice. The one caveat is that if the Caprice was originally equipped with the 350, you'll need to make some wiring changes to accomodate the top gear switch and TCC lockup control. An ECM from an '85 or later carb Caprice will take care of that, but the wires and T relay won't be present in the original body harness.

If the van is a dead donor vehicle, the 350, TH700-R4, ECM, and wire harness are all there.